Method in the electrodeposition of metals, and cathode suited for such purpose



Allg- 1934. K. w. PALMAER ET AL 1,970,975.

METHOD IN THE ELECTRODEPOSITION 0F METALS, AND

CATHODE SUITEDFOR SUCH PURPOSE Filed April 20. 1932 nun/m 2 7 i Eh. E J

Y 3% {mi/wflzwm Patented Aug. 21, 1934 PATENT OFFICE METHOD IN THE ELECTRODEPOSITION OF METALS, AND CATHODE SUITED FOR SUCH PURPOSE Knut Wilhelm Palmaer, Stockholm, and Oskar Emanuel Griep,

Appelviken,

Sweden; said Griep assignor to said Palmaer Application April 20, 1932, Serial No. 606,463 In Sweden May 8, 1931 ll? illaims.

The present invention relates to a method for the electro-deposition of metals, as well as to a cathode suited for such purpose. The method according to the invention which may be applied with advantage for instance to the-eleotro-deposition of the metals of the eighth group of the periodic system, such as iron, from solutions containing salts of one or more of the metals with the use of a cathode consisting of mercury flowing over a vertical or inclined bearer or support (preferably having plate-shape) is mainly characterized in that the mercury is supplied to the two sides of the bearer in two separate streams. Preferably the mercury is ejected from a supply device, e. g. a perforated pipe, against diverting or deflecting members, such as plates which are arranged so as to direct the mercury ejected against them from the mercury supply device towards the two sides'of the bearer. In a preferred embodiment those surface portions of the bearers, which are adapted for contact with mercury, are previously amalgamated. Preferably such diverting or deflectingmembers are used, which are previously amalgamated on those surface portions which will come in contact with the mercury. During the electrolysis the level Ell of the electrolyte in the electrolytic cell should be regulated so that the surface portions of the bearer which are flooded by mercury are completely immersed in the electrolyte.

According to the invention the bearer or support for the flowing cathode mercury consists of a metal plate over both sides of which mercury flows, and both sides of which act as cathode. In this connection the term plate is to be understood as comprising sheets, wire gauze etc. and generally a body, the width and length of which is considerable in relation to its thickness. Spirally twisted sheets or wire gauzes, hollow cylinders and the like are also included in the term plates. It has already been proposed to employ apq paratus in which a single stream of mercury is caused to impinge against the upper edge of a 5 vertical metal plate constituting the bearer or support for the cathode mercury, and flow in a downward direction on both sides of the plate.

According to the present invention the mercury is not supplied to the bearer or support directly in a single stream, but is divided, prior to its impinging on the support or the like into two separate streams, these two separate streams being supplied to the opposite sides of the support. a This provides an economical operation since a 55 more efiective utilization of the mercury for the purpose in view is thereby ensured. Further, especially due to the possibility of influencing each of said two separate streams prior to its contacting with the support, for instance through the action of amalgamated deflecting means, e. g. E surfaces, a hitherto unknown homogeneous distribution of the flowing mercury is obtained along both sides of said support. The mercury will coat both sides of the support as a thin cohering film and the support metal will not be exposed at any point. This is a distinct advantage, since irregularities in the flow of the mercury result in portions of the support metal being exposed whereby the current efiiciency drops because of hydrogen evolution due to the fact that the volt- 8'01? age necessary for depositing hydrogen on mercury is higher than that required for depositing hydrogen on any other metal. Moreover, if the electro'lyte is acid, for instance, the support metal may be directly attackedby the acid medium W at such exposed points or areas, which is detrimental if the support metal is less noble than mercury. A suitable embodiment of the cathode according to the invention will be described in. the following with reference to the attached so drawing in which Fig. I shows a cross section, Fig. 2 a side elevation and Fig. 3 a plan of the cathode according to the invention. At the upper border of the cathode plate proper 1 a circular pipe 2 is fastened by welding. One end of this pipe is kept closed as by means of a screwed-in plug 3. Said pipe is electrically connected to the negative pole of the current generator. The pipe 2 is provided along its upper portion with a plurality of minute apertures 4. When mercury is introduced through the end 5 of the pipe in such a quantity that the pipe becomes filled, the mercury will be squirted out-through the apertures 4. It has been found that a very uniform distribution of this ejected mercury may be obtained by arranging deflecting surfaces or members close by the holes 4, said members directing mercury ejected thereagainst from the supply device towards the two sides of the bearer.

To this end a sheet metal strip 6 of U- or V- 10 shaped cross section is disposed loosely on the upper side of the pipe 2 right on top of the holes so that the edges of the strip are supported by the mercury supply device (the pipe 2). The sheet metal strip is guided by a pair of pins 7 fastened to the pipe 2 and received by corresponding notches'8 at the ends of the strip. The strip 6 is raised due to the pressure of the mercury flowing out through the holes 4, said mercury striking the acutest or deepest portion of the no strip as seen in a cross-sectional view. Here the mercury is divided into two streams which pass separately through the outlet formed on each side of the median plane of the cathode between the edge in question of the U-shaped sheet metal strip and the periphery of the supply device (the pipe 2). These streams follow the pipe and flow downwards along both sides of the bearing plate 1. To obtain a good adhesion between the mercury and the metal parts those surface portions of the bearer, which are to come in contact with the mercury and/or those portions of the diverting or deflecting members, which come into contact with the mercury, should be previously amalgamated.

Of course the entire distributing device may be constructed in a number of other ways without departing from the spirit of the invention.

The essential inventive idea is that the bearer consists of a metal plate (the term plate being understood in the sense above indicated), over both sides of which mercury flows, and both sides of which serve as cathode. Hence the considerable advantage is gained that a given quantity of bearing material is utilized more effectively on account of the double-sided flow, than if only one side of the bearer were used to support the flowing mercury. Another essential feature is that the preferably plate-shaped carrier is provided with devices for supplying mercury to both of its sides in two'separate streams, it being possible to use a nozzle for the outflow of the mercury located close by each side of the bearer. Another, particularly important detail with respect to the realization of a good distribution of the mercury is, as stated above, that the bearer should co-operate with diverting or deflecting surfaces which-are disposed so as to direct mercury ejected thereagainst from the supply device back towards both sides of the bearer, the lastmentioned surfaces as well as those portions of the two sides of the bearer which come into contact with the mercury being, if desired, previously amalgamated to obtain a good adhesion between the mercury and the carrier. The deflecting member or members should be movably connected with the carrier. Thus, for instance, as described the deflecting member, when there is no flow of mercury, may rest loosely against a mercury supply pipe fastened to the bearing plate, said member being arranged to be easily raised by the pressure of the ejected mercury, the intermediate spaces between the edges of the deflecting member and the pipe acting as nozzles or outlets for the outflow of the deflected mercury against the bearing plate. The mercury outlet openings may be disposed anywhere between the deflecting member and the mercury supply device.

When using cathodes of the type described care should be taken that the level of the electrolyte in the electrolytic cell is regulated so that the bearer surface portions which are flooded by the mercury are completely immersed in the electrolyte so as to prevent the formation of unamalgamated spots and crystal crusts by the action of the oxygen of the air, or splashes from the electrolyte etc. which would cause an irregular flow of the mercury.

two separate streams prior to its impinging on the support, and supplying one of said two separate streams to each of the two sides of the support.

2. Method as defined in claim 1, wherein one of the two separate streams is sprayed onto each of the two sides of the support.

3. Method as defined in claim 1, wherein the mercury is sprayed against deflecting means disposed to divide the mercury ejected thereagainst and direct the resulting streams against the opposite sides of the support.

4. In the method for the electrodeposition of metals from solutions containing salts thereof by electrolyzing such solutions in contact with a cathode consisting of mercury flowing over a vertical or inclined support, the improvement which comprises ejecting mercury onto previously amalgamated deflecting means adapted to divide the mercury ejected thereagainst into two separate streams and disposed to direct one of such separate streams against each of the two sides of the support.

5. A method as defined in claim 1, wherein the surfaces of the support which are to come into contact with mercury are amalgamated prior to their use.

6. A method as defined in claim 4, wherein the surfaces of the support which are to come into contact with mercury are amalgamated prior to their use.

7. A method as defined in claim 1, wherein the level of the electrolyte is so regulated that the surface portions of the support over which the mercury flows are completely immersed in the electrolyte.

8. In apparatus for the electrodeposition of metals from solutions containing salts thereof by electrolyzing such solutions in contact. with a cathode consisting of mercury flowing over a vertical or inclined support, a support comprising a metal plate and means for dividing mercury supplied thereto into two separate streams, one for each side of said plate, prior to the mercury impinging on said plate.

9. Apparatus as defined in claim 8 wherein a mercury supply nozzle is disposed adjacent each side of said support.

10. Apparatus as defined in claim 8 comprising a mercury supply nozzle and deflecting means disposed to direct mercury ejected thereagainst from the supply nozzle towards both sides of the support.

11. Apparatus as defined in claim 8 comprising means for supplying mercury, at least one nozzle for ejecting mercury and means disposed to direct mercury ejected thereagainst from said nozzle towards both sides of the support, the mercury supply nozzle being disposed between the deflecting means and the means for supplying mercury 12. In apparatus for the electrodeposition of metals from solutions containing salts thereof by electrolyzing such solutions in contact with a cathode consisting of mercury flowing over a vertical or inclined support, a support comprising an amalgamated metal plate and means for dividing mercury supplied thereto into two separate streams, one for each side of said plate, prior to the mercury impinging on said plate.

13. In apparatus for the electrodeposition of metals from solutions containing salts thereof by electrolyzing such solutions in contact with a cathode consisting of vmercury flowing over a vertical or inclined support, a. support comprising a metal plate adapted for the flow of mercury upon both sides thereof, a mercury supply nozzle and amalgamated deflecting means disposed so as to direct mercury ejected thereagainst from the supply nomle towards the two sides of the support in two separate streams, one stream to each side of said support.

'14. Apparatus as defined in claim 13, wherein the metal support is amalgamated.

15. In apparatus for the electrodeposition of metals from solutions containing salts thereof by electrolyzing such solutions in contact with a. cathode consisting of mercury flowing over a vertical or inclined support, a support comprising a metal plate adapted for the flow of mercury upon both sides thereof, a perforated mercury supply pipe extending along the upper edge of said support and deflecting means adapted to direct the mercury issuing from the perforations against both sides of the support.

16. In apparatus for the electrodeposition of metals from solutions containing salts thereof by electrolyzing such solutions in contact with a cathode consisting of mercury flowing over a vertical or inclined support, a support comprising a metal plate adapted for the flow of mercury upon both sides thereof, a perforated mercury supply pipe extending along the upper edge of said support and deflecting means movably connected with the support and adapted to direct the mercury issuing from the perforations against both sides of the support.

1'7. In apparatus for the electrodeposition of metals from solutions containing salts thereof by electrolyzing such solutions in contact with a cathode consisting of mercury flowing over a vertical or inclined support, a support comprising a metal plate adapted for the flow of mercury upon both sides thereof, a perforated mercury supply pipe extending along the upper edge of said support and deflecting means freely sup- I 

